Mop-top Sri Lankan round-armer Lasith Malinga (No8) and England's T20 captain Stuart Broad (No10) are the only fast men in that top 10.

Now remember when T20 began and the dire predictions of the fate of the twirly types? McCullum does.

"It was touted as being the death of the spin bowler," he said from Colombo last night.

"But over the period of T20 [which began seriously in 2007 with the inaugural world championship] you can consistently see spinners in the top 10 and they continue to be the guys who can win or lose games for their sides."

McCullum made his debut at that tournament five years ago in South Africa. It was won by India. He played one match, against South Africa, as a batsman, then disappeared for the next eight T20s. Since winning a recall, he has been ever-present apart from missing one game in Sri Lanka in 2009, playing 33 out of 34 games.

So he knows his T20 oats.

"It's definitely changed as far as spin bowlers trying to bowl orthodox turn and bounce with every single ball," he said.

"It's not that now. It's about trying to stay ahead of the batsman, take wickets but also negate their strengths at the same time.

"There's only 120 balls [in an innings] and if you can try and secure dots then that creates pressure to gain wickets as well.

"Now you see bowlers adding things, all sorts of variations. You need to get better and not stay stagnant. Hopefully, I'm continuing to do that."

McCullum has taken 36 T20 wickets at 16.58 apiece. His lower order hitting is also handy. Captain Ross Taylor this week made it clear how highly he rates McCullum's role at the world championship.

"He has an outstanding T20 record and gives us options as an offspinner. He's very experienced in this form of the game and obviously more than likely he'll take the spot of one of the players [from the one-run win over India on Wednesday]."

When McCullum first came to prominence he was, perhaps inevitably, tagged the "other" McCullum.

Younger brother Brendon had already logged six years of international cricket, and was first choice wicketkeeper-batsman when Nathan made his debut.

They've taken different paths, and Nathan is still to win a test cap.

With Dan Vettori still ploughing along and others like legspinner Tarun Nethula being readied, he might not achieve that ambition. In any case, his game seems better suited to the demands of the limited-overs games.

He's a fine fielder, quick-footed and alert from his own bowling, and can hit a big ball late in the piece.

Nathan McCullum has not been as much a fixture in the 50-over game - having played 36 of 60 ODIs since making his debut in September 2009 - as the shortest form.

So for now, that's where his primary focus is. He was No3 on that ranking list "and it is something I have kept an eye on and been quite proud of. I want to try and get to the top, be No1-ranked bowler. If I can do that then I know I will be doing performances to get New Zealand across the line and be a dominant force in T20".

Unlike some players, McCullum appreciates the value of watching games he's not involved in.

"I've got a few kids in an academy in Dunedin and I tell them to learn as much as you can; always be picking up things. I was fortunate enough to spend five minutes with Ajmal during the Sri Lankan Premier League and he managed to teach me a little about bowling the doosra.

That's something I'll work on in the next 12 months and I've got a couple of other variations which hopefully I can bring to the fore in this tournament."

Speaking of which, McCullum fancies New Zealand's chances, but reckons several teams possess his four key ingredients for a successful T20 side: explosive batsmen who can clear the boundary; being smart; being a top class fielding outfit; and having quality spin and death bowlers.

"It's a matter of us being able to do that consistently in the tournament and get on a roll."